Work began on the development of emergency or bailout kits for the Army Air Corps in the mid-1930s, and accelerated immediately prior to World War II. The F-1 (for "forced landing") was standardized in May 1940. It was carried in a large silver-colored canvas bag, and contained two cans of rations and another can containing a flashlight, matches, compass, fishing line and hooks, gauze, iodine, and a bandage. The B-series (for "bailout") of parachute kits, first tested in a limited manner beginning in 1936, were stored in a large canvas pouch, and could also be attached to a parachute harness and used as back or seat cushions. The development of the B-1 mountain kit and the B-2 jungle kit eventually led to the B-4 that was standardized for aircraft serving in all climates in October 1942. Few of these newer kits reached combat theaters until fall 1943, however, as it was ordered that supplies of the B-1 and B-2 be exhausted first. The later B-5 kit was basically a B-4 that contained a copy of Army Air Forces manual 21W (arctic, jungle, and desert survival) and a poncho.

Survival vests (the C-1) were also developed in 1944 to supplement and eventually replace the B-series parachute kits. The C-1 vest was made of a heavy, tough canvas and had sixteen pocket that contained various items; a first aid kit, two cans of parachute rations, a water bladder, a pair of leather gloves, two flares, three ounces of oil, twelve fire starters and a striking surface, 40 matches, a strip of flint, a whistle, razor blades, a small knife with a regular blade and saw blade, a mosquito net, a signal mirror, a bandage, and a container of 20 .45 ACP shotshell cartridges. The vest also had a built-in holster and a waterproof cover for an M1911 pistol. The C-1 vest was intended to be used with the C-2 250-pound capacity one-man life raft.

The Army Air Corps (a part of the Army Air Forces from February 1942) also developed emergency kits for aircraft, prefixed with an "E-." Iterations were from E-1 to E-19. Some of the kits were designed for large aircraft and could sustain multiple men, while the E-3, E-3A, E-6, E-7, and E-17 were for one-man use. The E-6 and E-7 could be clipped to a parachute harness and held two K-rations and two cans of water, respectively. The E-3, E-3A, and E-17 were developed with the assistance of the War Department Military Intelligence Division, and were "secret," listed in only a few equipment manuals. They were devoid of any markings, and were also intended for use on covert missions of the MID. They were apparently found to be unsatisfactory, and relatively small numbers were produced in comparison to other kits.

The E-17 kit, stored in an olive drab webbing pouch, was standardized in June 1944. In the pouch were two waterproof plastic flasks, separated by an ESM/1 signal mirror.

General Equipment:

• Four one-ounce chocolate rations

• Four sticks of chewing gum

• Two packets of bouillon powder

• Ten double-edged razor blades

• Fish hooks and fishing line

• Small compass; it could be "swallowed if necessary and retrieved later."

• Sewing kit

• Three prophylactics

• Sharpening stone

• Matches

Medical Equipment:

• Sulfaguanidine (antibacterial)

• Sulfadiazine (antibacterial)

• Sulfanilamide (antibacterial)

• Halazone (water purifier)

• Atabrine (antimalarial)

• Benzedrine sulfate (amphetamine)

• Salt

• Adhesive compress bandage

• Toothbrush

• Adhesive tape

• Iodine

• Tweezers

• Ophthalmic ointment

Here is a web page with an exploded view of the contents of the E-17. Prophylactics are surprisingly useful in survival situations, and have been included in many U.S. military survival kits since WWII. Selected uses include:

• Water carrier

• Fire-starting materials carrier

• Elastic portion of a slingshot

• Rubber glove or hand covering

• Keeping contaminants out of the barrel of a firearm

• Fishing bobber

Source:

Sweeting, C.G. United States Army Aviators' Equipment, 1917-1945. Jefferson: McFarland & Company, 2015.

Did the USAAF and RAF really think their bomber crews were going to Casanova their way out of contested Europe?

/u/the_howling_cow has covered the US side of things quite splendidly, so I'd just add that their RAF counterparts didn't have condoms in their escape kits. British kits were largely the work of Clayton Hutton of MI9, a rather independently minded fellow who disliked official bureaucracy so initially procured large numbers of standard fifty cigarette tins that were filled with "malted milk sweets (provided by Horlicks), chewing gum, a bar of peanut blended food, water purifying tablets, a rubber bottle for water, a small saw, a bar of chocolate, Benzedrine tablets (for the purpose of keeping escapers awake at critical times), matches, a compass, thread, tape and two tissue maps (one of Germany and one of northern France)" (MI9’s Escape and Evasion Mapping Programme 1939 – 1945, Barbara Bond). The cigarette tin was later replaced with a [plastic case] (http://www.iwm.org.uk/collections/item/object/30083162); as rubber became scarce the case was redesigned as a plastic bottle with a screw top so the container itself could carry water, removing the need for the [rubber water bottle] (http://www.aucklandmuseum.com/collection/object/am_humanhistory-object-596002).